Chronograph Diffusers


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cm250
October 27, 2009, 06:50 PM
Hey all, just sent a money order off for a used Chrony F1 today, only thing wrong with it is that it's missing one diffuser. Was wondering if these have to be bought from Chrony or can you make your own. From what I have read they are just to reduce sunlight effects on a bright day. Have seen pics of other people's chronographs that look like they have home made diffusers on them. Was thinking about cutting a couple out of a white plastic 5 gallon bucket and adapting post/upright mounts to them.
What do you think, would that work?
Thanks for any info!
Tony

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1858
October 27, 2009, 08:02 PM
cm250, as I mentioned in the other thread, chrono sensors need contrast between the bullet and the background. My Chrony Beta Master manual suggests marking bullets with a black pen if the chronograph is showing Err1 or Err2 readings. The background should be as uniform in color/contrast as possible. An overcast sky, if light enough, is uniform. A solid white, non-translucent plastic is uniform and bright enough if there's sufficient ambient light. With solid screens, you may have an issue once the sun gets low in the sky or if you position the chrono under an awning or some other form of shade that reduces ambient light. So in summary, it's all about contrast between the bullet and the background. High contrast = good, low contrast = bad.

I made aluminum screens for my chronograph but the local range has an awning that casts a big shadow after about 2pm. The chronograph works great in bright sun but not so great as the ambient light decreases. I plan on modifying the screens to account for this.

:)

mongoose33
October 27, 2009, 09:08 PM
This is related to your issue--I have a chronograph I wanted to use indoors. If the light is from fluorescent lights, it'll screw up the sensors.

So I use a piece of tagboard/foamboard on top of the posts, and shine incandescent 100-watt bulbs in clamplights up at them. Works great:

http://clubdoctor.com/pics/chronosetup.jpg

Sorry about the bad cellphone pic.

If it's cloudy, you probably don't need diffusers; since what I'm using in the pic above works, anything that creates a translucent background should work fine so long as there's enough light. The point of the above pic is that you could even have a fairly large piece of translucent plastic--perhaps the side of a barrel or something--on top and it should work fine.

And if you want to use it at an indoor range, just duplicate the above.

Ol` Joe
October 27, 2009, 09:22 PM
The defusers actually give a brighter background for the sensors then a clear blue sky. A white clouded day is actually brighter to the sensors then the darker "blue" sky.
Shooting chrony sells the rods and defusers (don`t ask how I know) and they are easy enough to make at home if one wants. I`d go with a wood dowel in place of a metal rod if you do make your own, they likely won`t be as hard on the plastic housing if hit by a stray bullet.

bullseye308
October 28, 2009, 01:09 AM
I'd definitely replace the metal rods with wooden dowels. "If" you hit it, you won't damage your chronograph. At least that is what I hear. :uhoh:

ants
October 28, 2009, 05:39 AM
Wooden dowels and white milk jugs (some 5 gal buckets may be too dense to let enough light through from above). White milk jugs are free and work great.

Sport45
October 28, 2009, 07:19 AM
I thought about buying that chronograph myself. Looked like a pretty good deal.

If I had bought it, I was thinking I could buy one of those translucent 24" x 48" fluorescent light diffusers at Home Depot and make diffusers for both sensors for about $3.

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